Multi-band mobile communication device

ABSTRACT

Disclosed is a communication apparatus having a small-scale circuit used for modulation. A common transmission image rejection mixer ( 56 ) supplies transmission modulation frequencies to a plurality of quadrature modulators ( 23 ) (G, D, P, W). Accordingly, it is unnecessary to prepare the transmission image rejection mixer ( 56 ) for transmission signal types, makes it possible to prevent the circuit scale from increasing.

TECHNICAL FIELD

The present invention relates to a multiband mobile communicationapparatus in compliance with various mobile communication systems suchas GSM (Global System for Mobile Communications), DCS (Digital CellularSystem), PCS (Personal Communications Service), and UMTS (UniversalMobile Telecommunications System).

BACKGROUND ART

A mobile communication terminal such as a cellular phone modulatesquadrature baseband signals I and Q for transmission. A local oscillatorsupplies a frequency used for the modulation via an image rejectionmixer.

In Europe, for example, a cellular phone is requested for transmissioncorrespondingly to different communication systems such as GSM, DCS,PCS, and UMTS. These communication systems use different frequencies fortransmission. Consequently, the local oscillator and the image rejectionmixer are needed for each communication system.

However, providing each communication system with the local oscillatorand the image rejection mixer may increase the circuit scale of themobile communication terminal.

It is therefore an object of the present invention to provide acommunication apparatus having a small-scale circuit used formodulation.

DISCLOSURE OF THE INVENTION

The present invention relates to a communication apparatus. Thecommunication apparatus according to the present invention comprises aplurality of transmission modulation means, a first local oscillationmeans, a second local oscillation means, and a transmission modulationfrequency output means.

The transmission modulation means is provided for each transmissionsignal type and modulates a transmission signal based on a transmissionmodulation frequency. A first local oscillation means generates a firstsignal within a specified range of frequencies. A second localoscillation means generates a second signal within a specified range offrequencies. Based on the first and second signals, the transmissionmodulation frequency output means supplies the transmission modulationfrequency to the transmission modulation means.

The common transmission modulation frequency output means supplies atransmission modulation frequency to a plurality of transmissionmodulation means. This eliminates the need for providing thetransmission modulation frequency output means correspondingly to atransmission signal type, preventing the circuit scale from increasing.

Since the transmission modulation frequency output means provides thetransmission modulation frequency, the first and second signals'frequencies need not correspond to those specified for the transmissionsignal types. This makes it possible to narrow a range of changingfrequencies for the first and second signals, preventing the circuitscale of the first local oscillation means and the second localoscillation means from increasing.

It is desirable to further provide the communication apparatus accordingto the present invention with a plurality of reception demodulationmeans, a fixed local oscillation means, and a reception demodulationfrequency output means.

The reception demodulation means is provided for each reception signaltype and demodulates a reception signal based on the receptiondemodulation frequency. The fixed local oscillation means generates afixed frequency signal having specified frequency. The receptiondemodulation frequency output means provides a reception demodulationfrequency to the reception demodulation means based on output from thefirst local oscillation means and the fixed frequency signal.

The common reception demodulation frequency output means supplies thereception demodulation frequency to a plurality of receptiondemodulation means. In addition, the reception demodulation frequencyoutput means uses a reception local oscillation means used by thetransmission modulation frequency output means. Since the transmissionmodulation frequency output means and the reception demodulationfrequency output means commonly use the reception local oscillationmeans, it is unnecessary to provide the reception local oscillationmeans for transmission and reception, preventing the circuit scale fromincreasing.

Moreover, the communication apparatus according to the present inventioncan be configured as follows. Another communication apparatus accordingto the present invention comprises a fixed local oscillation means, atransmission modulation means, a third local oscillation means, and atransmission signal output means.

The fixed local oscillation means generates a fixed frequency signalhaving specified frequency. The transmission modulation means modulatesa transmission signal based on the fixed frequency signal frequency. Athird local oscillation means generates a third signal within aspecified range of frequencies. The transmission signal output meanschanges a transmission modulation means' output frequency to a sum ordifference between the third signal's frequency and the transmissionmodulation means' output frequency, and outputs the frequency for eachtransmission signal type.

The transmission signal output means need not be provided for eachtransmission signal type, preventing the circuit scale from increasing.

Further, the transmission signal output means adjusts the transmissionsignal frequency to a frequency specified for each transmission signaltype. Frequencies of the third signal and an output from thetransmission modulation means need not correspond to those specified fortransmission signal types. This makes it possible to narrow a range ofchanging frequencies for the third signal, preventing the circuit scaleof the third local oscillation means.

It is desirable to further provide the communication apparatus accordingto the present invention with a plurality of reception demodulationmeans, a fourth local oscillation means, and a reception demodulationfrequency output means.

The reception demodulation means is provided for each reception signaltype and demodulates a reception signal based on the receptiondemodulation frequency. The fourth local oscillation means generates afourth signal within a specified range of frequencies. Based on anoutput from the fourth local oscillation means and the fixed frequencysignal, the reception demodulation frequency output means supplies thereception demodulation frequency to the reception demodulation means.

The common reception demodulation frequency output means supplies thereception demodulation frequency to a plurality of receptiondemodulation means. In addition, the reception demodulation frequencyoutput means uses the fixed local oscillation means used by thetransmission modulation frequency output means. Since the transmissionmodulation frequency output means and the reception demodulationfrequency output means commonly use the fixed local oscillation means,it is unnecessary to independently provide the fixed local oscillationmeans, preventing the circuit scale from increasing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of atransmission/reception apparatus 1 according to a first embodiment ofthe present invention;

FIG. 2A shows a configuration of a quadrature demodulator 13G or 13W;

FIG. 2B shows a configuration of a quadrature demodulator 13D or 13P;

FIG. 3A shows a configuration of a quadrature modulator 23G;

FIG. 3B shows a configuration of a quadrature modulator 23D or 23P;

FIG. 3C shows a configuration of a quadrature modulator 23W;

FIG. 4 shows an internal configuration of an amplifier 24 (G, D, P, W);

FIG. 5 shows an internal configuration of a fixed local oscillator block52;

FIG. 6 shows an internal configuration of a reception local oscillatorblock 53;

FIG. 7 shows an internal configuration of a transmission localoscillator block 54;

FIG. 8 shows an internal configuration of a reception image rejectionmixer 55;

FIG. 9 shows an internal configuration of a transmission image rejectionmixer 56;

FIG. 10 is a block diagram showing a configuration of thetransmission/reception apparatus 1 according to a second embodiment ofthe present invention;

FIG. 11 shows an internal configuration of a modulator 32;

FIG. 12 shows an internal configuration of an offset PLL section 35;

FIG. 13 shows an internal configuration of an amplifier 37 (G, D, P);and

FIG. 14 shows an internal configuration of a transmission localoscillator block 54.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described in further detailwith reference to the accompanying drawings.

First Embodiment

FIG. 1 is a block diagram showing a configuration of atransmission/reception apparatus 1 according to the first embodiment ofthe present invention. The transmission/reception apparatus 1 comprisesa reception section 10, a transmission section 20, a VC-TCXO 51, a fixedlocal oscillator block 52, a reception local oscillator (first localoscillation means) 53, a transmission local oscillator (second localoscillation means) 54, a reception image rejection mixer (receptiondemodulation frequency output means) 55, a transmission image rejectionmixer (transmission modulation frequency output means) 56, a duplexer62, a high-frequency switch 64, a UMTS antenna 72, and a triple-bandantenna 74.

The triple-band antenna 74 is used to transmit or receive GSM, DCS, andPCS signals. The high-frequency switch 64 outputs the GSM, DCS, and PCSsignals received by the triple-band antenna 74 to the reception section10 and outputs the GSM, DCS, and PCS signals output from thetransmission section 20 to the triple-band antenna 74.

The UMTS antenna 72 is used to transmit or receive a UMTS (WCDMA)signal. The duplexer 62 outputs the UMTS (WCDMA) signal received by theUMTS antenna 72 to the reception section 10 and outputs the UMTS (WCDMA)signal output from the transmission section 20 to the UMTS antenna 72.That is to say, the duplexer 62 separates a transmission signal from areception signal. Since UMTS (WCDMA) assumes continuous transmission andreception, the duplexer 62 is used instead of a switch.

The reception section 10 comprises a band pass filter (BPF) 11 (G, D,P), a variable gain low noise amplifier 12 (G, D, P, W), a quadraturedemodulator 13 (G, D, P, W) (reception demodulation means), a variablegain amplifier 14 (I, Q), an LPF 15 (I, Q), an LPF 16 (I, Q), a variablegain amplifier 17 (I, Q), and a DC amplifier 18 (I, Q).

The BPF 11G eliminates an interference signal except the frequency bandused for GSM from a signal output from the high-frequency switch 64, andoutputs the signal to the variable gain low noise amplifier 12G. The BPF11D eliminates an interference signal except the frequency band used forDCS from a signal output from the high-frequency switch 64, and outputsthe signal to the variable gain low noise amplifier 12D. The BPF 11Peliminates an interference signal except the frequency band used for PCSfrom a signal output from the high-frequency switch 64, and outputs thesignal to the variable gain low noise amplifier 12P.

The variable gain low noise amplifier 12G amplifies an output from theBPF 1G and supplies the output to the quadrature demodulator 13G. Thevariable gain low noise amplifier 12D amplifies an output from the BPF11D and supplies the output to the quadrature demodulator 13D. Thevariable gain low noise amplifier 12P amplifies an output from the BPF11P and supplies the output to the quadrature demodulator 13P. Thevariable gain low noise amplifier 12W amplifies an output from theduplexer 62 and supplies the output to the quadrature demodulator 13W.The variable gain low noise amplifier 12 (G, D, P, W) generates a smallnoise during amplification.

The quadrature demodulator 13 (G, D, P, W) quadrature-demodulates anoutput from the variable gain low noise amplifier 12 (G, D, P, W). FIGS.2A and 2B illustrate configurations of the quadrature demodulator 13 (G,D, P, W).

An internal configuration of the quadrature demodulator 13G will now bedescribed with reference to FIG. 2A. The quadrature demodulator 13Gincludes a frequency mixer 131G, a frequency mixer 132G, and a ½ divider133G. The frequency mixers 131G and 132G respectively mix outputs fromthe variable gain low noise amplifier 12G and the ½ divider 133G andsupply them to the variable gain amplifiers 14I and 14Q. The ½ divider133G divides an output from the reception image rejection mixer 55 foroutput. At this time, the ½ divider 133G supplies the frequency mixers131G and 132G with output signals that are orthogonal to each other. Thevariable gain low noise amplifier 12G and the ½ divider 133G generatethe same output frequency. This can provide the direct demodulation(direct conversion) method.

An internal configuration of the quadrature demodulator 13W will now bedescribed with reference to FIG. 2A. The quadrature demodulator 13Wincludes a frequency mixer 131W, a frequency mixer 132W, and a ½ divider133W. The frequency mixers 131W and 132W respectively mix outputs fromthe variable gain low noise amplifier 12W and the ½ divider 133W andsupply them to the LPFs 16I and 16Q. The ½ divider 133W divides anoutput from the reception image rejection mixer 53 for output. At thistime, the ½ divider 133W supplies the frequency mixers 131W and 132Wwith output signals that are orthogonal to each other. The variable gainlow noise amplifier 12W and the ½ divider 133W generate the same outputfrequency. This can provide the direct demodulation (direct conversion)method.

An internal configuration of the quadrature demodulator 13D will now bedescribed with reference to FIG. 2B. The quadrature demodulator 13Dincludes a frequency mixer 131D, a frequency mixer 132D, and a polyphasefilter 134D. The frequency mixers 131D and 132D respectively mix outputsfrom the variable gain low noise amplifier 12D and the polyphase filter134D and supply them to the variable gain amplifiers 14I and 14Q. Thepolyphase filter 134D receives an output from the reception imagerejection mixer 55 and supplies the frequency mixers 131D and 132D withoutput signals that are orthogonal to each other. The variable gain lownoise amplifier 12D and the polyphase filter 134D generate the sameoutput frequency. This can provide the direct demodulation (directconversion) method.

An internal configuration of the quadrature demodulator 13P will now bedescribed with reference to FIG. 2B. The quadrature demodulator 13Pincludes a frequency mixer 131P, a frequency mixer 132P, and a polyphasefilter 134P. The frequency mixers 131P and 132P respectively mix outputsfrom the variable gain low noise amplifier 12P and the polyphase filter134P and supply them to the variable gain amplifiers 14I and 14Q. Thepolyphase filter 134P receives an output from the reception imagerejection mixer 55 and supplies the frequency mixers 131P and 132P withoutput signals that are orthogonal to each other. The variable gain lownoise amplifier 12P and the polyphase filter 134P generate the sameoutput frequency. This can provide the direct demodulation (directconversion) method.

The variable gain amplifier 14I amplifies outputs from the frequencymixers 131G, 131D, and 131P of the quadrature demodulators 13G, 13D, and13P and supplies them to the LPF 15I. The variable gain amplifier 14Qamplifies outputs from the frequency mixers 132G, 132D, and 132P of thequadrature demodulators 13G, 13D, and 13P and supplies them to the LPF15Q. The LPFs 15I and 15Q eliminate interference signals from outputs ofthe variable gain amplifiers 14I and 14Q, and output the quadraturebaseband signals I and Q. For example, interference signals maybe foundin the bands such as adjacent channels except frequencies to be used.

The variable gain amplifiers 14I and 14Q and the variable gain low noiseamplifiers 12G, 12D, and 12P can control gains. This makes it possibleto provide control to allow a uniform amplitude for an input signal toan A/D converter included in a digital processing circuit (not shown)for processing the quadrature baseband signals I and Q. Control on aninput signal amplitude for the A/D converter is needed to alwaysmaintain a constant input dynamic range of the A/D converter.

The LPF 16I removes an interference signal from an output of thefrequency mixer 131W of the quadrature demodulator 13W and supplies theoutput to the variable gain amplifier 17I. The LPF 16Q removes aninterference signal from an output of the frequency mixer 132W of thequadrature demodulator 13W and supplies the output to the variable gainamplifier 17Q. The LPFs 16I and 16Q remove interference signals from anoutput of the quadrature demodulator 13W for output. The variable gainamplifiers 17I and 17Q amplify outputs of the LPFs 16I and 16Q andoutput the quadrature baseband signals I and Q.

The DC amplifier 18I amplifies an output of the variable gain amplifier17I and supplies it to an input of the LPF 16I. The DC amplifier 18Qamplifies an output of the variable gain amplifier 17Q and supplies itto an input of the LPF 16Q. This means supplying an output of thequadrature demodulator 13W with DC feedback from the DC amplifiers 18Iand 18Q. The DC feedback is effective for canceling a DC offset.

The following describes why the DC feedback is supplied to an output ofthe quadrature demodulator 13W while no DC feedback is supplied tooutputs of the quadrature demodulators 13G, 13D, and 13P. The DCfeedback works so as to remove low pass frequencies. Normally, a lowpass cut-off frequency is approximately 2 kHz. The quadraturedemodulator 13W processes a WCDMA signal. The WCDMA signal has a 2 MHzband and is sufficiently wider than GSM, DCS, and PCS bands according tothe TDMA method. A lack of the low pass frequency as high as 2 kHz inthe GSM, DCS, and PCS disables normal reception. Since the WCDMA signalhas the wide band, however, information included in the signal is notlost significantly due to a lack of the 2 kHz low pass frequency.Therefore, normal reception is available if the DC feedback is suppliedto an output of the quadrature demodulator 13W.

The variable gain amplifiers 16I and 16Q and the variable gain low noiseamplifier 12W can control gains. This makes it possible to providecontrol to allow a uniform amplitude for an input signal to an A/Dconverter included in the digital processing circuit (not shown) forprocessing the quadrature baseband signals I and Q. Control on an inputsignal amplitude for the A/D converter is needed to always maintain aconstant input dynamic range of the A/D converter.

The transmission section 20 has LPFs 21 (I, Q), LPFs 22 (I, Q),quadrature modulators 23 (G, D, P, W) (transmission modulation means),amplifiers 24 (G, D, P, W), LPFs 25 (G, D, P), and an isolator 26.

The LPFs 21 (I, Q) remove interference signals from the quadraturebaseband signals I and Q of the GSM, DCS, and PCS and output the signalsto the quadrature modulators 23 (G, D, P).

The LPF 21I removes an interference signal from the GSM's quadraturebaseband signal I and outputs the signal to the quadrature modulator23G. The LPF 21I removes an interference signal from the DCS'squadrature baseband signal I and outputs the signal to the quadraturemodulator 23D. The LPF 21I removes an interference signal from the PCS'squadrature baseband signal I and outputs the signal to the quadraturemodulator 23P.

The LPF 21Q removes an interference signal from the GSM's quadraturebaseband signal Q and outputs the signal to the quadrature modulator23G. The LPF 21Q removes an interference signal from the DCS'squadrature baseband signal Q and outputs the signal to the quadraturemodulator 23D. The LPF 21Q removes an interference signal from the PCS'squadrature baseband signal Q and outputs the signal to the quadraturemodulator 23P.

The LPFs 22 (I, Q) remove interference signals from the UMTS'squadrature baseband signals I and Q and output the signals to thequadrature modulator 23W. The LPF 22I removes an interference signalfrom the UMTS's quadrature baseband signal I and outputs the signal tothe quadrature modulator 23W. The LPF 22Q removes an interference signalfrom the UMTS's quadrature baseband signal Q and outputs the signal tothe quadrature modulator 23W.

The quadrature modulators 23 (G, D, P) quadrature-modulate outputs ofthe LPFs 21 (I, Q) based on a transmission modulation frequency outputfrom a transmission image rejection mixer 56. The quadrature modulator23W quadrature-modulates outputs of the LPFs 22 (I, Q) based on atransmission modulation frequency output from the transmission imagerejection mixer 56. FIGS. 3A through 3C show configurations of thequadrature modulators 23 (G, D, P, W). FIG. 3A diagrams the quadraturemodulator 23G. FIG. 3B diagrams the quadrature modulators 23D and 23P.FIG. 3C diagrams the quadrature modulator 23W.

An internal configuration of the quadrature modulator 23G will bedescribed with reference to FIG. 3A. The quadrature modulator 23Gincludes a frequency mixer 231G, a frequency mixer 232G, a polyphasefilter 233G, an adder 234G, and a ½ divider 235G.

The frequency mixer 231G mixes outputs of the LPF 21I and the polyphasefilter 233G and outputs a result to the adder 234G. The frequency mixer232G mixes outputs of the LPF 21Q and the polyphase filter 233G andoutputs a result to the adder 234G. The polyphase filter 233G receives adivided output of the transmission image rejection mixer 56 and outputsa signal whose phases are orthogonal to each other. The adder 234G addsan output of the frequency mixer 231G and that of the frequency mixer232G and outputs a result. The ½ divider 235G divides an output of thetransmission image rejection mixer 56 and outputs a result to thetransmission image rejection mixer 56. The LPFs 21I and 21Q and thepolyphase filter 233G generate the same output frequency. This canprovide the direct modulation (direct conversion) method.

An internal configuration of the quadrature modulator 23D will bedescribed with reference to FIG. 3B. The quadrature modulator 23Dincludes a frequency mixer 231D, a frequency mixer 232D, a polyphasefilter 233D, and an adder 234D.

The frequency mixer 231D mixes outputs of the LPF 21I and the polyphasefilter 233D and outputs a result to the adder 234D. The frequency mixer232D mixes outputs of the LPF 21Q and the polyphase filter 233D andoutputs a result to the adder 234D. The polyphase filter 233D receives adivided output of the transmission image rejection mixer 56 and outputsa signal whose phases are orthogonal to each other. The adder 234D addsan output of the frequency mixer 231D and that of the frequency mixer232D and outputs a result. The LPFs 21I and 21Q and the polyphase filter233D generate the same output frequency. This can provide the directmodulation (direct conversion) method.

An internal configuration of the quadrature modulator 23P will bedescribed with reference to FIG. 3B. The quadrature modulator 23Pincludes a frequency mixer 231P, a frequency mixer 232P, a polyphasefilter 233P, and an adder 234P.

The frequency mixer 231P mixes outputs of the LPF 21I and the polyphasefilter 233P and outputs a result to the adder 234P. The frequency mixer232P mixes outputs of the LPF 21Q and the polyphase filter 233P andoutputs a result to the adder 234P. The polyphase filter 233P receives adivided output of the transmission image rejection mixer 56 and outputsa signal whose phases are orthogonal to each other. The adder 234P addsan output of the frequency mixer 231P and that of the frequency mixer232P and outputs a result. The LPFs 21I and 21Q and the polyphase filter233P generate the same output frequency. This can provide the directmodulation (direct conversion) method.

An internal configuration of the quadrature modulator 23W will bedescribed with reference to FIG. 3C. The quadrature modulator 23Wincludes a frequency mixer 231W, a frequency mixer 232W, an adder 234W,and a polyphase filter 236W.

The frequency mixer 231W mixes outputs of the LPF 21I and the polyphasefilter 236W and outputs a result to the adder 234W. The frequency mixer232W mixes outputs of the LPF 22Q and the polyphase filter 236W andoutputs a result to the adder 234W. The polyphase filter 233W receives adivided output of the transmission image rejection mixer 56 and outputsa signal whose phases are orthogonal to each other. The adder 234W addsan output of the frequency mixer 231W and that of the frequency mixer232W and outputs a result. The LPFs 22I and 22Q and the polyphase filter233W generate the same output frequency. This can provide the directmodulation (direct conversion) method.

The amplifiers 24 (G, D, P, W) amplify or otherwise process outputs ofthe quadrature modulators 23 (G, D, P, W). FIG. 4 shows an internalconfiguration of the amplifiers 24 (G, D, P, W).

The amplifiers 24 (G, D, P, W) include variable gain high frequencyamplifiers 241 (G, D, P, W), band pass filters 242 (G, D, P, W), andpower amplifiers 243 (G, D, P, W). The variable gain high frequencyamplifiers 241 (G, D, P, W) amplify outputs of the quadrature modulators23 (G, D, P, W). However, the gain is controllable and can correspond toa high frequency signal input. The band pass filters 242 (G, D, P, W)remove an interference signal such as an adjacent channel from outputsof the variable gain high frequency amplifiers 241 (G, D, P, W) andoutputs a result. The power amplifiers 243 (G, D, P, W) amplify outputsof the band pass filters 242 (G, D, P, W).

The LPFs 25 (G, D, P) remove interference signals from output signals ofthe amplifiers 24 (G, D, P) and output the signals to the high-frequencyswitch 64. The isolator 26 outputs a signal from the amplifier 24W tothe duplexer 62.

The VC-TCXO 51 supplies a reference signal for PLL control to the fixedlocal oscillator block 52, the reception local oscillator block 53, andthe transmission local oscillator block 54. For example, the VC-TCXO 51generates the reference signal at a frequency of 19.2 MHz.

An internal configuration of the fixed local oscillator block 52 willnow be described with reference to FIG. 5. The fixed local oscillatorblock 52 includes a local oscillator 521, a fixed PLL control section522, an LPF 523, and a variable ½ divider 524.

The local oscillator 521 inside the fixed local oscillator block 52generates a fixed-frequency signal. For example, the frequency is fixedto 3,040 MHz. The fixed PLL control section 522 compares, in terms ofphases, an output signal of the local oscillator 521 with the PLLcontrol reference signal output from the VC-TCXO 51 and outputs a phasecomparison difference. The LPF 523 passes low pass components of thephase comparison difference and supplies a result to the localoscillator 521.

Further, the internal configuration of the fixed local oscillator block52 including a local oscillator 521, a fixed PLL control section 522, anLPF 523, and a variable ½ divider 524 is as follows. The localoscillator 521 outputs a signal in phase synchronization with the PLLcontrol reference signal output from the VC-TCXO 51. The variable ½divider 524 divides and outputs an output of the local oscillator 521.The dividing ratio can be changed in accordance with signal types. Forexample, the frequency is changed to one fourth when GSM and DCS signalsare received, or to one eighth when a PCS signal is received. An outputof the variable ½ divider 524 becomes an output of the fixed localoscillator block 52.

An internal configuration of the reception local oscillator block 53will now be described with reference to FIG. 6. The reception localoscillator block 53 includes a local oscillator 531, a PLL controlsection for channel control 532, and an LPF 533.

The local oscillator 531 inside the reception local oscillator block 53can change frequencies of signals to be generated. For example,frequencies can be changed within a range of 3,930 to 4,340 MHz. In moredetail, it may be preferable to change frequencies in the range 4,080 to4,220 MHz when receiving a GSM signal; in the range 3,990 to 4,140 MHzwhen receiving a DCS signal; in the range 4,050 to 4,170 MHz whenreceiving a PCS signal; and in the range 4,220 to 4,340 MHz whenreceiving a UMTS signal. The PLL control section for channel control 532compares, in terms of phases, an output signal of the local oscillator531 with the PLL control reference signal output from the VC-TCXO 51 andoutputs a phase comparison difference. The LPF 533 passes low passcomponents of the phase comparison difference and supplies a result tothe local oscillator 531.

Further the internal configuration of the reception local oscillatorblock 53 including a local oscillator 531, a PLL control section forchannel control 532, and an LPF 533 is as follows. The local oscillator531 outputs a signal in phase synchronization with the PLL controlreference signal output from the VC-TCXO 51. An output of the localoscillator 531 becomes an output (first signal) of the reception localoscillator block 53.

An internal configuration of the transmission local oscillator block 54will now be described with reference to FIG. 7. The transmission localoscillator block 54 includes a local oscillator 541, a PLL controlsection for channel control 542, and an LPF 543.

The local oscillator 541 inside the transmission local oscillator block54 can change frequencies of signals to be generated. For example,frequencies can be changed within a range of 4,400 to 4,780 MHz. In moredetail, it may be preferable to change frequencies in the range 4,640 to4,780 MHz when receiving a GSM signal; in the range 4,560 to 4,710 MHzwhen receiving a DCS signal; in the range 4,400 to 4,520 MHz whenreceiving a PCS signal; and in the range 4,600 to 4,720 MHz whenreceiving a UMTS signal. The PLL control section for channel control 542compares, in terms of phases, an output signal of the local oscillator541 with the PLL control reference signal output from the VC-TCXO 51 andoutputs a phase comparison difference. The LPF 543 passes low passcomponents of the phase comparison difference and supplies a result tothe local oscillator 541.

The internal configuration of the transmission local oscillator block 54including a local oscillator 541, a PLL control section for channelcontrol 542, and an LPF 543 is as follows. The local oscillator 541outputs a signal in phase synchronization with the PLL control referencesignal output from the VC-TCXO 51. An output of the local oscillator 541becomes an output (second signal) of the transmission local oscillatorblock 54.

An internal configuration of the reception image rejection mixer 55 willnow be described with reference to FIG. 8. The reception image rejectionmixer 55 includes a ½ divider 551, a ¼ divider 552, frequency mixers 553and 554, an adder 555, and a band pass filter 556.

The ½ divider 551 halves an output of the reception local oscillatorblock 53 and supplies a result to each of the frequency mixers 553 and554. The ¼ divider 552 quarters an output of the fixed local oscillatorblock 52 and supplies a result to each of the frequency mixers 553 and554. The ¼ divider 552 outputs signals whose phases are orthogonal toeach other. The frequency mixers 553 and 554 mix outputs of the ½divider 551 and the ¼ divider 552 and supply outputs to the adder 555.The adder 555 adds the outputs of the frequency mixers 553 and 554 andproduces an output. A BPF 556 passes only a specified band in the outputof the adder 555. The output of the BPF 556 becomes an output of thereception image rejection mixer 55. The frequency of this output becomesa modulated frequency for reception.

An internal configuration of the transmission image rejection mixer 56will now be described with reference to FIG. 9. The transmission imagerejection mixer 56 includes a ½ divider 561, a polyphase filter 562,frequency mixers 563 and 564, an adder 565, and a band pass filter 566.

The ½ divider 561 halves the output (second signal) of the transmissionlocal oscillator block 54 and supplies a result to each of the frequencymixers 563 and 564. The polyphase filter 562 supplies the frequencymixers 563 and 564 with the output (first signal) of the reception localoscillator block 53 as two signals orthogonal to each other. Thefrequency mixers 563 and 564 mix outputs of the divider 561 and thepolyphase filter 562 and supplies outputs to the adder 565. The adder565 adds the outputs of the frequency mixers 563 and 564 and produces anoutput. A BPF 566 passes only a specified band in the output of theadder 565. The output of the BPF 566 becomes an output of thetransmission image rejection mixer 56. The frequency of this outputbecomes a transmission modulation frequency.

Operations of the first embodiment will now be described.

First, a reception operation will be described. When the triple-bandantenna 74 receives GSM, DCS, and PCS signals, the high-frequency switch64 sends the received signals to the band pass filters 11 (G, D, P) inaccordance with the signal types. The signals sent to the BPFs 11 (G, D,P) are then sent to the quadrature demodulators 13 (G, D, P) via thevariable gain low noise amplifiers 12 (G, D, P). The quadraturedemodulators 13 (G, D, P) demodulate the input signals which are thenconverted into quadrature baseband signals I and Q via the variable gainamplifiers 14 (I, Q) and the LPFs 15 (I, Q).

When the UMTS antenna 72 receives a UMTS (WCDMA) signal, the duplexer 62sends the received signal to the quadrature demodulator 13W via thevariable gain low noise amplifier 12W. The quadrature demodulator 13Wdemodulates the input signal. The modulated signal is converted into thequadrature baseband signals I and Q via the LPFs 16 (I, Q) and thevariable gain amplifiers 17 (I, Q). The DC amplifiers 18 (I, Q) supply aDC feedback to remove a DC offset.

During demodulation by the quadrature demodulators 13 (G, D, P, W),there must be correspondence between various signal bands (925 to 960MHz for GSM; 1,805 to 1,880 MHz for DCS; 1,930 to 1,990 MHz for PCS; and2,110 to 2,170 MHz for UMTS) and signal frequency bands supplied to thefrequency mixers 131 and 132 (G, D, P, W) based on the signal outputfrom the reception image rejection mixer 55. Since the fixed localoscillator block 52 and the reception local oscillator block 53 areconfigured as mentioned above, the frequency bands correspond to eachother. This will be proved for each signal type.

When a GSM signal is received, the local oscillator 521 oscillates afrequency of 3,040 MHz; the variable ½ divider 524 provides a dividingratio of ¼; and the local oscillator 531 oscillates frequencies rangingfrom 4,080 to 4,220 MHz. The ½ divider 551 supplies the frequency mixers553 and 554 with signal frequencies ranging from 2,040 MHz (4,080×(½))to 2,110 MHz (4,220×(½)). The ¼ divider 552 supplies the frequencymixers 553 and 554 with a signal frequency of 190 MHz (3,040×(¼)×(¼)).Therefore, the reception image rejection mixer 55 outputs signalfrequencies ranging from 1,850 MHz (2,040−190) to 1,920 MHz (2,110−190).A signal output from the reception image rejection mixer 55 is halved bythe ½ divider 133G and is supplied to the frequency mixers 131G and132G. The signal frequencies range from 925 MHz (1,850/2) to 960 MHz(1,920/2).

When a DCS signal is received, the local oscillator 521 oscillates afrequency of 3,040 MHz; the variable ½ divider 524 provides a dividingratio of ¼; and the local oscillator 531 oscillates frequencies rangingfrom 3,990 to 4,140 MHz. The ½ divider 551 supplies the frequency mixers553 and 554 with signal frequencies ranging from 1,995 MHz (3,990×(½))to 2,070 MHz (4,140×(½)). The ¼ divider 552 supplies the frequencymixers 553 and 554 with a signal frequency of 190 MHz (3,040×(¼)×(¼)).Therefore, the reception image rejection mixer 55 outputs signalfrequencies ranging from 1,850 MHz (1,995−190) to 1,880 MHz (2,070−190).A signal output from the reception image rejection mixer 55 is suppliedto the frequency mixers 131D and 132D via the polyphase filter 134D. Thesignal frequencies range from 1,805 to 1,880 MHz.

When a PCS signal is received, the local oscillator 521 oscillates afrequency of 3,040 MHz; the variable ½ divider 524 provides a dividingratio of ⅛; and the local oscillator 531 oscillates frequencies rangingfrom 4,050 to 4,170 MHz. The ½ divider 551 supplies the frequency mixers553 and 554 with signal frequencies ranging from 2,025 MHz (4,050×(½))to 2,085 MHz (4,170×(½)). The ¼ divider 552 supplies the frequencymixers 553 and 554 with a signal frequency of 95 MHz (3,040×(⅛)×(¼)).Therefore, the reception image rejection mixer 55 outputs signalfrequencies ranging from 1,930 MHz (2,025−190) to 1,990 MHz (2,085−190).A signal output from the reception image rejection mixer 55 is suppliedto the frequency mixers 131P and 132P via the polyphase filter 134P. Thesignal frequencies range from 1,930 to 1,990 MHz.

When a UMTS signal is received, the local oscillator 521 oscillatesfrequencies ranging from 4,220 to 4,340 MHz. Therefore, the receptionimage rejection mixer 55 outputs signal frequencies ranging from 4,220to 4,340 MHz. A signal output from the reception image rejection mixer55 is supplied to the frequency mixers 131W and 132W via the polyphasefilter 133W. The signal frequencies range from 2,110 (4,220/2) to 2,170MHz (4,340/2).

The following describes a transmission operation. The quadraturemodulators 23 (G, D, P) quadrature-modulate baseband signals I and Q forGSM, DCS, and PCS via the LPFs 21 (I, Q). Outputs of the quadraturemodulators 23 (G, D, P) are supplied to the high-frequency switch 64 viathe amplifiers 24 (G, D, P) and the LPFs 25 (G, D, P). An output of thehigh-frequency switch 64 is transmitted from the triple-band antenna 74.

The quadrature modulator 23W quadrature-modulates baseband signals I andQ for UMTS via the LPFs 22 (I, Q). An output of the quadrature modulator23W is sent to the duplexer 62 via the amplifier 24W and the isolator26. An output of the duplexer 62 is transmitted from the UMTS antenna72.

During demodulation by the quadrature modulators 23 (G, D, P, W), theremust be correspondence between various signal bands (880 to 915 MHz forGSM; 1,710 to 1,785 MHz for DCS; 1,850 to 1,910 MHz for PCS; and 1,920to 1,980 MHz for UMTS) and signal frequency bands supplied to thefrequency mixers 231 and 232 (G, D, P, W) based on the signal outputfrom the reception image rejection mixer 56. Since the reception localoscillator block 53 and the transmission local oscillator block 54 areconfigured as mentioned above, the frequency bands correspond to eachother. This will be proved for each signal type.

When a GSM signal is transmitted, the local oscillator 531 oscillatesfrequencies ranging from 4,080 to 4,220 MHz; and the local oscillator541 oscillates frequencies ranging from 4,640 to 4,780 MHz. The ½divider 561 supplies the frequency mixers 563 and 564 with signalfrequencies ranging from 2,320 MHz (4,640×(½)) to 2,390 MHz (4,780×(½)).The polyphase filter 562 supplies the frequency mixers 563 and 564 withsignal frequencies ranging from 4,080 to 4,220 MHz. Therefore, thetransmission image rejection mixer 56 outputs signal frequencies rangingfrom 1,760 MHz (4,080−2,320) to 1,830 MHz (4,220−2,390). A signal outputfrom the transmission image rejection mixer 56 is halved by the ½divider 235G and is supplied to the frequency mixers 231G and 232G. Thesignal frequencies range from 880 MHz (1,760/2) to 915 MHz (1,830/2).

When a DCS signal is transmitted, the local oscillator 531 oscillatesfrequencies ranging from 3,990 to 4,140 MHz; and the local oscillator541 oscillates frequencies ranging from 4,560 to 4,710 MHz. The ½divider 561 supplies the frequency mixers 563 and 564 with signalfrequencies ranging from 2,280 MHz (4,560×(½)) to 2,355 MHz (4,710×(½)).The polyphase filter 562 supplies the frequency mixers 563 and 564 withsignal frequencies ranging from 3,990 to 4,140 MHz. Therefore, thetransmission image rejection mixer 56 outputs signal frequencies rangingfrom 1,710 MHz (3,990−2,280) to 1,785 MHz (4,140−2,355). A signal outputfrom the transmission image rejection mixer 56 is supplied to thefrequency mixers 231D and 232D via the polyphase filter 233D. The signalfrequencies range from 1,710 to 1,785 MHz.

When a PCS signal is transmitted, the local oscillator 531 oscillatesfrequencies ranging from 4,050 to 4,170 MHz; and the local oscillator541 oscillates frequencies ranging from 4,400 to 4,520 MHz. The ½divider 561 supplies the frequency mixers 563 and 564 with signalfrequencies ranging from 2,200 MHz (4,400×(½)) to 2,260 MHz (4,520×(½)).The polyphase filter 562 supplies the frequency mixers 563 and 564 withsignal frequencies ranging from 4,050 to 4,170 MHz. Therefore, thetransmission image rejection mixer 56 outputs signal frequencies rangingfrom 1,850 MHz (4,050−2,200) to 1,910 MHz (4,170−2,260). A signal outputfrom the transmission image rejection mixer 56 is supplied to thefrequency mixers 231P and 232P via the polyphase filter 233P. The signalfrequencies range from 1,850 to 1,910 MHz.

When a UMTS signal is transmitted, the local oscillator 531 oscillatesfrequencies ranging from 4,220 to 4,340 MHz; and the local oscillator541 oscillates frequencies ranging from 4,600 to 4,720 MHz. The ½divider 561 supplies the frequency mixers 563 and 564 with signalfrequencies ranging from 2,300 MHz (4,600×(½)) to 2,360 MHz (4,720×(½)).The polyphase filter 562 supplies the frequency mixers 563 and 564 withsignal frequencies ranging from 4,220 to 4,340 MHz. Therefore, thetransmission image rejection mixer 56 outputs signal frequencies rangingfrom 1,920 MHz (4,220−2,300) to 1,980 MHz (4,340−2,360). A signal outputfrom the transmission image rejection mixer 56 is supplied to thefrequency mixers 231G and 232G via the polyphase filter 236D. The signalfrequencies range from 1,920 to 1,980 MHz.

According to the first embodiment, the common transmission imagerejection mixer 56 supplies transmission modulation frequencies to aplurality of quadrature modulators 23 (G, D, P, W). Consequently, thiseliminates the need for providing the transmission image rejection mixer56 to respective transmission signal types, preventing the circuit scalefrom increasing.

Since the transmission image rejection mixer 56 supplies modulationfrequencies, frequencies generated from the transmission localoscillator block 54 and the reception local oscillator block 53 need notcorrespond to those specified for the transmission signal types.Accordingly, it is possible to narrow a range of changing frequenciesgenerated from the transmission local oscillator block 54 and thereception local oscillator block 53, preventing the circuit scale ofthese oscillators from increasing. For example, the transmission localoscillator block 54 may use the single local oscillator 541. Thetransmission local oscillator 53 may use the single local oscillator531. The use of VCOs can easily implement the local oscillators 531 and541.

Moreover, the common reception image rejection mixer 55 suppliesreception demodulation frequencies to a plurality of quadraturedemodulators 13. In addition, the reception image rejection mixer 55uses the reception local oscillator block 53 the transmission imagerejection mixer 56 uses. Since the transmission image rejection mixer 56and the reception image rejection mixer 55 share the reception localoscillator block 53, it is unnecessary to prepare the reception localoscillator block 53 for transmission and reception, preventing thecircuit scale from increasing.

Second Embodiment

The second embodiment differs from the first embodiment in the systemconfiguration used for transmission of GSM, DCS, and PCS signals.

FIG. 10 is a block diagram showing a configuration of thetransmission/reception apparatus 1 according to the second embodiment ofthe present invention. The transmission/reception apparatus 1 accordingto the second embodiment comprises a reception section 10, atransmission section 30, a VC-TCXO 51, a fixed local oscillator block52, a reception local oscillator (fourth local oscillation means) 53, atransmission local oscillator (third local oscillation means) 54, areception image rejection mixer (reception demodulation frequency outputmeans) 55, a duplexer 62, a high-frequency switch 64, a UMTS antenna 72,and a triple-band antenna 74. Hereinafter, the mutually correspondingparts in the first and second embodiments are designated by the samereference numerals and a detailed description is omitted for simplicity.

The reception section 10, the VC-TCXO 51, the fixed local oscillatorblock 52, the reception local oscillator (fourth local oscillationmeans) 53, the reception image rejection mixer (reception demodulationfrequency output means) 55, the duplexer 62, the high-frequency switch64, the UMTS antenna 72, and the triple-band antenna 74 are the same asthose for the first embodiment. It should be noted that an output of thereception local oscillator (fourth local oscillation means) 53 isreferred to as a fourth signal.

The transmission section 30 includes LPFs 31 (I, Q), a modulator(transmission modulation means) 32, an LPF 33, an offset PLL section(transmission signal output means) 35, amplifiers 37 (G, D, P), LPFs 38(G, D, P), LPFs 22 (I, Q), a quadrature modulator 23W, a amplifier 24W,and an isolator 26.

The LPFs 22 (I, Q), the quadrature modulator 23W, the amplifier 24W, andthe isolator 26 are the same as those for the first embodiment.

The LPFs 31 (I, Q) remove interference signals from the quadraturebaseband signals I and Q for GSM, DCS, and PCS and supply the signals tothe modulator 32.

An internal configuration of the modulator 32 will now be described withreference to FIG. 11. The modulator 32 modulates a transmission signalbased on the frequency output from the fixed local oscillator block 52.The modulator 32 includes frequency mixers 321 and 322, a ½ divider 323,and an adder 324. The frequency mixers 321 and 322 mix outputs of theLPFs 31 (I, Q) and of the ½ divider 323. The ½ divider 323 halves anoutput of the fixed local oscillator block 52 and supplies a result toeach of the frequency mixers 321 and 322. The frequency mixers 321 and322 are supplied with outputs whose phases are orthogonal to each other.The adder 324 adds outputs of the frequency mixers 321 and 322 andgenerates an output. The output of the adder 324 is equivalent to thatof the modulator 32.

The LPF 33 supplies the offset PLL section 35 with low pass componentsin an output of the adder 324.

An internal configuration of the offset PLL section 35 will now bedescribed with reference to FIG. 12. The offset PLL section 35 includesa PFD 351, low pass filters 352 (G, D, P), local oscillators 353 (G, D,P), a frequency mixer 354, and a low pass filter 355.

The PFD 351 compares an output of the low pass filter 355 with anoutput, phase, and frequency of the LPF 33 and outputs a comparisonresult to the low pass filters 352 (G, D, P) according to the signaltypes. This provides control to supply the PFD 351 with equal outputfrequencies from the low pass filter 355 and the LPF 33. The low passfilters 352 (G, D, P) pass low pass components in an output of the PFD351. In accordance with outputs from the low pass filters 352 (G, D, P),the local oscillators 353 (G, D, P) change frequencies of the outputsignals. The frequency mixer 354 mixes outputs of the local oscillators353 (G, D, P) with an output of the variable ½ divider 544 in thetransmission local oscillator block 54 and supplies an output. The lowpass filter 355 passes low pass components in the output from thefrequency mixer 354. The outputs of the local oscillator 353 (G, D, P)are equivalent to those of the offset PLL section 35.

An internal configuration of the amplifier 37 (G, D, P) will now bedescribed with reference to FIG. 13. The amplifier 37 (G, D, P) includesa band pass filter 371 (G, D, P) and a power amplifier 372 (G, D, P).The band pass filter 371 (G, D, P) removes an interference signalbypassing components within a specified band of an output from theoffset PLL section 35. The power amplifier 372 (G, D, P) amplifies andgenerates an output from the band pass filter 371 (G, D, P). The outputof the band pass filter 371 (G, D, P) is equivalent to that of theamplifier 37 (G, D, P).

The LPF 38 (G, D, P) supplies the high-frequency switch 64 with low passcomponents in an output from the amplifier 37 (G, D, P).

An internal configuration of the transmission local oscillator block 54will now be described with reference to FIG. 14. The transmission localoscillator block 54 includes a local oscillator 541, a PLL controlsection for channel control 542, an LPF 543, and a variable ½ divider544.

The local oscillator 541 can change frequencies of signals to begenerated. For example, frequencies can be changed within a range of3,840 to 4,340 MHz. In more detail, it may be preferable to changefrequencies in the range 4,000 to 4,280 MHz when transmitting a GSMsignal; in the range 4,180 to 4,330 MHz when transmitting a DCS signal;in the range 4,080 to 4,200 MHz when transmitting a PCS signal; and inthe range 3,840 to 3,960 MHz when transmitting a UMTS signal. Like thefirst embodiment, an output of the local oscillator 541 is supplied tothe quadrature modulator 23W. The PLL control section for channelcontrol 542 compares, in terms of phases, a signal output from the localoscillator 541 with the PLL control reference signal output from theVC-TCXO 51 and generates a phase comparison difference. The LPF 543passes low pass components of the phase comparison difference andsupplies a result to the local oscillator 541.

Further, the internal configuration of the transmission local oscillatorblock 54 including a local oscillator 541, a PLL control section forchannel control 542, an LPF 543, and a variable ½ divider 544 is asfollows. The local oscillator 541 outputs a signal in phasesynchronization with the PLL control reference signal output from theVC-TCXO 51. The variable ½ divider 544 divides a frequency of the signaloutput from the local oscillator 541 and outputs a result to thefrequency mixer 354. The dividing ratio can be changed in accordancewith the signal types. For example, the signal is output to thefrequency mixer 354 by dividing the frequency by 8 during GSM signaltransmission or by 2 during DCS or PCS signal transmission. An outputfrom the variable ½ divider 544 is referred to as a third signal.

The following describes operations according to the second embodiment.

Operations for receiving GSM, DCS, PCS, and UMTS signals andtransmitting UMTS signals are the same as those for the firstembodiment. The following describes operations for transmitting GSM,DCS, and PCS signals.

The modulator 32 quadrature-modulates baseband signals I and Q for GSM,DCS, and PCS via the LPF 31 (I, Q). An output of the modulator 32 issent to the offset PLL section 35 via the LPF 33. An output from theoffset PLL section 35 is sent to the high-frequency switch 64 via theamplifier 37 (G, D, P) and the LPF 38 (G, D, P). An output from thehigh-frequency switch 64 is transmitted from the high-frequency switch64.

There must be correspondence between various signal bands (880 to 915MHz for GSM; 1,710 to 1,785 MHz for DCS; and 1,850 to 1,910 MHz for PCS)and signal frequency bands of the local oscillator 353 (G, D, P) in theoffset PLL section 35. According to the second embodiment, these bandscorrespond to each other. This will be proved for each signal type.

When a GSM signal is transmitted, the local oscillator 521 oscillates afrequency of 3,040 MHz; the variable ½ divider 524 provides a dividingratio of ¼; the local oscillator 541 oscillates frequencies ranging from4,000 to 4,280 MHz; and the variable ½ divider 544 provides a dividingratio of ⅛. When the modulator 32 supplies the PFD 351 with a signal viathe LPF 33, the signal's frequency is the same as that output from the ½divider 323, i.e., 380 MHz (3,040×(¼)×(½)). When the frequency mixer 354supplies a signal to the PFD 351 via the low pass filter 355, thesignal's frequency is the sum of the frequency of a signal supplied tothe frequency mixer 354 from the transmission local oscillator block 54and the frequency oscillated from the local oscillator 353G in FIG. 12.The transmission local oscillator block 54 supplies the frequency mixer354 with a signal having frequencies ranging from 500 (4,000×(⅛)) to 535MHz (4,280×(⅛)). Therefore, the local oscillator 353G oscillatesfrequencies ranging from 880 (500+380) to 915 MHz (535+380).

When a DCS signal is transmitted, the local oscillator 521 oscillates afrequency of 3,040 MHz; the variable ½ divider 524 provides a dividingratio of ¼; the local oscillator 541 oscillates frequencies ranging from4,180 to 4,330 MHz; and the variable ½ divider 544 provides a dividingratio of ½. When the modulator 32 supplies the PFD 351 with a signal viathe low pass filter 355, the signals frequency is the same as thatoutput from the ½ divider 323, i.e., 380 MHz (3,040×(¼)×(½)). When thefrequency mixer 354 supplies a signal to the PFD 351 via the low passfilter 355, the signals frequency is a difference between the frequencyof a signal supplied to the frequency mixer 354 from the transmissionlocal oscillator block 54 and the frequency oscillated from the localoscillator 353D in FIG. 12. The transmission local oscillator block 54supplies the frequency mixer 354 with a signal having frequenciesranging from 2,090(4,180×(½)) to 2,165 MHz (4,330×(½)). Therefore, thelocal oscillator 353D oscillates frequencies ranging from1,710(2,090−380) to 1,785 MHz (2,165−380).

When a PCS signal is transmitted, the local oscillator 521 oscillates afrequency of 3,040 MHz; the variable ½ divider 524 provides a dividingratio of ⅛; the local oscillator 541 oscillates frequencies ranging from4,080 to 4,220 MHz; and the variable ½ divider 544 provides a dividingratio of ½. When the modulator 32 supplies the PFD 351 with a signal viathe LPF 33, the signal's frequency is the same as that output from the ½divider 323, i.e., 190 MHz (3,040×(⅛)×(½)). When the frequency mixer 354supplies a signal to the PFD 351 via the low pass filter 355, thesignal's frequency is a difference between the frequency of a signalsupplied to frequency mixer 354 from the transmission local oscillatorblock 54 and the frequency oscillated from the local oscillator 353P inFIG. 12. The transmission local oscillator block 54 supplies thefrequency mixer 354 with a signal having frequencies ranging from2,040(4,080×(½)) to 2,100 MHz (4,200×(½)). Therefore, the localoscillator 353P oscillates frequencies ranging from 1,850(2,040−190) to1,910 MHz (2,100−190).

The second embodiment eliminates the need for providing the offset PLLsection 35 to respective transmission signal types, preventing thecircuit scale from increasing.

Further, the offset PLL section 35 adjusts a transmission signalfrequency to the frequency specified for each transmission signal type.Therefore, frequencies output from the transmission local oscillatorblock 54 and the modulator 32 need not correspond to those specified forthe transmission signal types. As a result, it is possible to narrow arange of changing frequencies generated from the transmission localoscillator block 54, preventing the circuit scale of this oscillatorfrom increasing. For example, the transmission local oscillator block 54may use the single local oscillator 541. The use of VCOs can easilyimplement the local oscillator 541.

Moreover, the common reception image rejection mixer 55 suppliesreception demodulation frequencies to a plurality of quadraturedemodulators 13. In addition, the reception image rejection mixer 55uses the fixed local oscillator block 52 the modulator 32 uses. Sincethe modulator 32 and reception image rejection mixer 55 share the fixedlocal oscillator block 52, it is unnecessary to prepare the fixed localoscillator block 52 independently, preventing the circuit scale fromincreasing.

1. A communication apparatus comprising: a fixed local oscillation meansfor generating a fixed frequency signal having a specified frequency; atransmission modulation means for modulating a transmission signal basedon a frequency of the fixed frequency signal; a third local oscillationmeans for generating a third signal having a frequency within aspecified range; a transmission signal output means which changes afrequency output from the transmission modulation means to a sum or adifference between a frequency of the third signal and a frequencyoutput from the transmission modulation means and outputs the frequencyin accordance with a type of the transmission signal; a plurality ofreception demodulation means which is provided for reception signaltypes and demodulates the reception signal based on a receptiondemodulation frequency; a fourth local oscillation means for generatinga fourth signal having a frequency within a specified range; and areception demodulation frequency output means for supplying thereception demodulation frequency to the reception demodulation meansbased on output of the fourth local oscillation means and the fixedfrequency signal.